Electron discharge device construction



21, 1969 KlYOSHl UCHIMARU E L 3,423,632

' ELECTRON DISCHARGE DEVICE CONSTRUCTION Filed Dec. 8, 1965 Sheet of 2 INVENTORS KIYOSHI UCHIMARU TE TS URO OTANI 2 ATTORNEYS.

Jan. 21, 1969 KlYOSHl UCHIMARU E AL ELECTRON DISCHARGE DEVICE CONSTRUCTION Filed Dec. 8, 1965 'Sheet 3 of 2 INVENTORS K I YOS UCHI RU T5 T5 U 0 TA W; ATTO NEYS.

United States Patent ELECTRON DISCHARGE DEVICE CONSTRUCTION Kiyoshi Uchimaru and Tetsuro Otani, Tokyo, Japan, as-

signors to Nippon Electric Company, Limited, Tokyo,

Japan, a corporation of Japan Filed Dec. 8, 1965, Ser. No. 513,664

US. Cl. 315-39.69 3 Claims Int. Cl. H01p 23/22, /58

ABSTRACT OF THE DISCLOSURE A device and method for constructing an anode assembly for a magnetron is described. A pair of substantially similar cylindrically shaped anode blocks are formed with inwardly facing polypetalous apertures. On one axial side of the blocks a groove is formed which is concentric with the cylinder axis and crosses the anode vane between the apertures. A pair of strap rings are formed with each provided with a plurality of projections angularly spaced at intervals corresponding to the angular spacing of alternate grooves in the anode vane. The rings are then mounted within the grooves with radial clearance and projections electrically bonded to the anode blocks. The blocks are mounted with the grooves facing one another to form an anode assembly for a magnetron having centrally located straps.

This invention relates to electron discharge devices and more particularly to anode assemblies for such devices of the magnetron type.

The invention, together with the various objects, features and advantages thereof and the manner of attaining them will become more apparent and the manner of attaining them will be best understood by the reference to the following description of the invention taken in conjunction with the accompanying drawing, in which:

FIG. 1A is a top view of a conventional anode assembly;

FIG. 1B is a cross sectional view taken along the line AA' of FIG. 1A;

FIG. 1C is a cross sectional view taken along the line BB of FIG. 1A;

FIGS. 2 through 5 show a series of illustrations depicting various stages in the fabrication of an anode assembly according an embodiment of this invention;

FIG. 2A being a top view of an anode block of the anode assembly prior to soldering a strap ring thereon;

FIG. 2B being a cross sectional view of the anode block taken along the line C-C of FIG. 2A;

FIG. 3 being a perspective view of a strap ring;

FIG. 4 being a cross sectional view of the anode block taken along the line C-C' of FIG. 2A and showing the strap ring fitted into an annular groove in the block, and

FIG. 5 being a cross sectional view of a completed anode assembly consisting of two similar anode blocks of the type shown in FIG. 4 which have been stacked in back-to-back relationship;

FIG. 6 is a cross sectional view of an anode assembly similar to that of FIG. 5 but modified in that two dissimilar blocks are stacked in back-to-back relationship and the position of the strap rings is not centrally located, and

FIGS. 7 through 9 show sectional views of anode assemblies in accordance with further embodiments of the invention.

Those knowledgeable in the art are aware that oscillations at frequencies determined by the geometry of cavity resonators incorporated in an anode assembly are sustained with electron discharge devices of the magnetron type and also that strapping is a common technique for separating the desirable oscillation frequency in the 1r mode from additional modes at spurious oscillation frequencies. Furthermore, it has long been recognized that a center-strapped anode has several advantages over endstrapped anodes, in that the straps can be made symmetrical and electrically balanced, and that reduced coupling between the strap and the end section of the anode can be achieved. However, center-strapped anodes were heretofore rarely constructed because of substantial manufacturing difficulties, and if constructed, they lacked the geometrical precision required for anode structures.

FIGS. 1A, 1B and 1C illustrate a center-strapped anode assembly of conventional construction. In fabricating this assembly two kinds of anode vanes having different geometrical configurations 2 and 3 and two strap rings 4 must be properly soldered within an anode shell 1. A number of technical difficulties are encountered with the fabrication of such conventional center-strapped anode assemblies. One of these difficulties results from too many soldering locations, viz soldering between the anode shell 1 and each of the anode vanes 2 and 3, between the anode vanes 2 and the anode vanes 3, and between the anode vanes 2 and one of the strap rings 4. Another is fabrication ditficulties, and is due to various reasons, such as the geometry of various component parts, the problem of achieving an even melting state of the solder during soldering, leakage of solder to the interior surfaces of the cavity resonators, and other lesser reasons.

As a result of these difficulties, uniformity from product to product in the fabrication of such conventional structures, cannot be obtained despite painstaking and time-consuming work. Further, as a result of variations in the spacing between adjacent anode vanes and variations in the cavity resonators, a wide difference in both the oscillation frequency and the oscillation output is unavoidable with these anode assemblies. Still further disadvantages are encountered, among which are a de graded frequency spectrum in the oscillation output, unstable oscillation conditions, and others.

Accordingly, it is an object of this invention to provide improved high-precision center-strapped anode assembly structures free from the above described disadvantages. Another object is to provide such structures having a design which will permit ease of machining and fabrication thereof.

In accordance with an aspect of this invention, construction of the assembly is achieved by providing a polypetalous hole or aperture in a generally cylindrical copper blank by piercing in the axial direction thereof to form a plurality of anode vanes, machining an annular groove in the back surfaces of these anode vanes, placing a strap ring in the annular groove, and stacking a plurality of such anode blocks arranged in back-to-back relationship one upon another in coaxial relationship.

The construction of anode assemblies according to this invention will now be described in specific detail in conjunction with the accompanying drawing. Referring first to FIGS. 2A and 2B, each of the anode blocks 5 of which an anode assembly according to this invention is composed is provided with a polypetalous hole 6 perforated in the axial direction of an oXygen-freehighconductivity cylindrical blank. This blank is preferably made 'of copper, but may also be of other suitably high conductivity materials. A plurality of anode vanes 7 are arranged in spaced symmetry about the axis of the cylinder, and an annular groove 8 is cut in the anode block vanes in the manner illustrated. The hole 6 is of high precision, and this hole and the anode vanes 7 can be formed by pressing a hob of a polypetalous form or die into the copper anode blank by the know cold hob'bing method. This method is advantageously employed for mass production manufacturing.

FIG. 3 shows a strap ring 9 which is to be placed in the annular groove 8. This ring 9 is provided with a plurality of projections 10 on one side thereof at equal intervals so as to correspond in spacing to alternate anode vanes of an anode block 5. FIG. 4 shows a longitudinal cross sectional view of the anode block 5 with the strap ring 9 soldered to the base of the annular groove 8 in the block. More specifically, the strap ring 9 is placed in the groove 8 concentrically with the anode block 5 and the projections are soldered to the groove base of alternate anode vanes 7. Because of the use of the strap ring 9 with its projections 10, the annular groove 8 in the anode block 5 will have the same width, depth, and height dimensions with respect to the individual anode vanes. As a result, the groove can be machined with one stroke on a lathe, thus aifording substantial time and cost economies.

FIG. 5 illustrates a center-strapped anode assembly consisting of two similar anode blocks 5 arranged in back-to-back relationship in such manner that projectionsoldered anode vanes of one anode block may face with projection-unsoldered anode vanes of the other anode 'block. A suitable high-frequency output hole (not illustrated) to be coupled with any one of the cavity resonators 6 must, of course, be provided in the side wall of such anode assembly.

Since a plurality of cavity resonators 6 are precisionmachined 'by the cold hobbing method and the number of soldering portions within the cavity resonators is reduced to as small a number as possible with the anode assembly of FIG. 5, variations of the oscillation frequency and the oscillation output are substantially reduced, the output frequency spectrum is improved, and unstable operation caused by variations in the resonator dimensions is also reduced.

Additiona ly, since the groove 8 is of the same dimensions with respect to all the anode vanes 7, it is merely necessary to bring any one of the projections 10 on the strap ring 9 in coincidence with any one of the anode vanes 7 in searching for the proper position of the strap ring in the groove before soldering, provided that the ring is concentric with the anode. Still another advantage with this construction is that by arranging the two anode blocks 5 in back-to-back relationship, it is merely necessary to bring a projection-soldered anode vane in coincidence with a projection-unsoldered anode vane. Thus the anode assembly of this invention has the distinct advantage that it can be fabricated with extreme ease and requires no particular skill as compared with the conventional anode assembly of FIG. 1.

Although the constructional features of this invention have thus far been described in connection with a specific embodiment of this invention in which two similar anode blocks are stacked 'back-to-back so as to form a centerstrapped anode assembly, it will be clear that various modifications thereof are possible within the scope of the invention. Several of these are illustrated in FIGS. 6 through 9.

The anode assembly shown in FIG. 6 is a modification of that shown in FIG. 5 in that two dissimilar anode blocks are stacked in 'back-to-back relationship and hence the strap rings are not centrally situated in the assembly.

Each of FIGS. 7 and 8 shows an anode assembly incorporating a plurality of strap n'ng pairs, the embodiment of FIG. 8 employing a pair of strap rings of larger anode members each'are formed diameter in each of the top and the bottom anode blocks. Any of the above anode assemblies according to this invention permits application of facings 11 for all anode vanes in order to protect the strapping from electron bombardment as exemplified by the embodiment of FIG. 9.

While the foregoing description sets forth the principles of the invention in connection with specific apparatus, it is to be understood that the description is made only by Way of example and not as a limitation of the scope of the invention as set forth in the objects thereof and in the accompanying claims.

What is claimed is:

1. A center strapped anode assembly for an electron discharge device of the magnetron type comprising a pair of substantially similar anode blocks,

each anode block being provided with like radially inwardly extending anode vanes uniformly distributed about and concentrically with a common axis and radially inwardly terminating at a common internal cylindrical surface,

said vanes further being shaped to define uniformly peripherally distributed polypetalous apertures,

with the vanes of said blocks being provided at one common axial end with like curved grooves of constant cross-section aligned along a common circumference concentric with the axis,

the grooves in said respective blocks being formed with like cross-sectional shape and arranged along oommon circumferences of like diameter,

the axially located bottoms of the grooves terminating within said blocks,

a pair of like diameter strap rings sized to fit with radial clearance within the annular grooves,

with each of said rings being provided with a plurality of projections extending axially from an axial side thereof,

said projections being numbered and spaced to contact alternate vanes within the grooves,

said blocks being stacked in back-to-back relationship with the grooves facing one another and with said vanes in angular registration,

a strap ring being positioned in each of said grooves with the projections of each ring in electrical contact with the axial groove bottoms of alternate vanes.

2. The invention described in claim 1 wherein said generally in the shape of a cylinder.

3. The invention described in claim 1 wherein the axial lent gh of one of said anode members is different from that of the other of said members.

References Cited UNITED STATES PATENTS 2,837,696 6/1958 La Rue 3l539.69 X 3,027,488 3/1962 Winsor 3l539.69 X 3,045,147 7/1962 Butler 31539.69 3,058,029 10/1962 Clampitt et al. 31539.69

HERMAN KARL SAALBACH, Primary Examiner. S. CHATMON, JR., Assistant Examiner.

US. Cl. X.R. 3l539.75 

